Did You Just Make an Expression?

an algebraic expression that is….. Today’s was a lesson I took out of a Kagan book called “Cooperative Learning and Mathematics Grades K-8”. I’ve never been to a Kagan workshop, but now I would love to go. We worked with writing algebraic expression. Here is how my period was spent.

1. I had the students sitting in groups of four, and had them number themselves one through four.

2. I had a paper sack and showed the kids that I was placing five beans in the bag. I then showed them that I was placing another six beans in the bag. I told them to discuss within their group what kind of number sentence I would write to describe the situation I had just showed them. I then asked all #2’s to write their number sentence on the board. I took out all of the beans to start the new example. I grabbed a small handful of beans and placed them in the bag and then showed them that I placed three more beans in the bag. Of course some of the kids started saying, “Mrs. Kerr, you didn’t tell us how many beans you put in at first.” I just smiled, and they quickly responded with, “Oh yeah, nevermind.” I then told them to discuss within their groups what the number sentence that would describe the situation that I had just showed them. Some of the answers varied, but most of them were correct. We discussed why the ones that were wrong would be wrong and discussed why we got x + 3 for the correct answer.

3. I then told them that I was putting the bag up and they were going to have to do the same thing within their group by listening to my story. After I gave them each scenario, we discussed the answers and why. Here were my verbal instructions:
1. I started with x beans, then I increased it by 10. (x + 10)
2. There were b beans in the bag. Now there are 7 less. ( b – 7)
3. I started with q beans in the bag and decreased it by 4. (q – 4)
4. There were n beans in the bag. Now there are 2 more. (n + 2)

4. I paired the 1’s and 2’s and the 3’s and 4’s in each group and gave them the “Pairs Check” worksheet. I had them check their answers with their partners and then actually had them check it with the other pair in their group.

5. I then put the expression x + 9 on the board and asked the pairs to come up with a word problem that would go with that expression. The kids had a little harder time understanding until some of the kids started giving their word problem. I then put the expression x – 9 on the board and asked them to do the same thing and then we shared their answers.